Medical Editor: John P. Cunha, DO, FACOEP
Symmetrel (amantadine hydrochloride) is an anti-Parkinson and an antiviral drug prescribed to prevent or treat symptoms of infection caused by strains of influenza A virus. Symmetrel is also used in the treatment of Parkinson's Disease and similar conditions. Symmeterel is available in generic form. Common side effects of Symmetrel include:
- stomach upset,
- loss of appetite,
- sleep problems (insomnia),
- strange dreams,
- nervous feeling,
- dry mouth,
- dry nose,
- blurred vision, or
- loss of balance or coordination.
Tell your doctor if you have unlikely but serious side effects of Symmetrel including:
- purplish-red blotchy spots on the skin,
- swelling of the ankles or feet,
- difficulty urinating, or
- vision changes.
The adult daily dosage of Symmeterel is 200 mg per day, taken orally. The dose for patients over 65 is 100 mg per day, and the pediatric dose is calculated based on the child's weight. Doses may be modified based on your medical condition and your response to therapy. Do not take Symmeterel if you have taken flu vaccine inhaled through the nose, as serious adverse reactions may occur. Symmetrel may interact with atropine, dicyclomine, glycopyrrolate, hyoscyamine, mepenzolate, methscopolamine, propantheline, scopolamine, quinine, quinidine, diuretics (water pills), or phenothiazines. Tell your doctor all medications and supplements you use. Symmeterel should not be used during pregnancy unless needed as it can cause heart defects in the fetus. It is not recommended for women who are nursing as it can pass into breast milk. Do not suddenly stop taking Symmeteral as symptoms or side effects may worsen.
Our Symmetrel Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.
Call your doctor at once if you have:
- extreme drowsiness, falling asleep suddenly even after feeling alert;
- a light-headed feeling, like you might pass out;
- shortness of breath (even with mild exertion), swelling in your hands or feet;
- painful or difficult urination;
- depression, agitation, aggression, behavior changes, hallucinations, thoughts of hurting yourself;
- a seizure; or
- severe nervous system reaction--very stiff (rigid) muscles, high fever, sweating, confusion, fast or uneven heartbeats, tremors.
You may have increased sexual urges, unusual urges to gamble, or other intense urges while taking this medicine. Talk with your doctor if this occurs.
Side effects may be more likely in older adults.
Common side effects may include:
- dizziness, falls;
- dry mouth;
- swelling in your legs or feet;
- nausea, constipation; or
- sleep problems (insomnia).
Read the entire detailed patient monograph for Symmetrel (Amantadine Hydrochloride)
Less frequently (1-5%) reported adverse reactions are: depression, anxiety and irritability, hallucinations, confusion, anorexia, dry mouth, constipation, ataxia, livedo reticularis, peripheral edema, orthostatic hypotension, headache, somnolence, nervousness, dream abnormality, agitation, dry nose, diarrhea and fatigue.
Infrequently (0.1-1%) occurring adverse reactions are: congestive heart failure, psychosis, urinary retention, dyspnea, skin rash, vomiting, weakness, slurred speech, euphoria, thinking abnormality, amnesia, hyperkinesia, hypertension, decreased libido, and visual disturbance, including punctate subepithelial or other corneal opacity, corneal edema, decreased visual acuity, sensitivity to light, and optic nerve palsy.
Rare (less than 0.1%) occurring adverse reactions are: instances of convulsion, leukopenia, neutropenia, eczematoid dermatitis, oculogyric episodes, suicidal attempt, suicide, and suicidal ideation (see WARNINGS).
Other adverse reactions reported during postmarketing experience with SYMMETREL (amantadine hydrochloride) usage include:
coma, stupor, delirium, hypokinesia, hypertonia, delusions, aggressive behavior, paranoid reaction, manic reaction, involuntary muscle contractions, gait abnormalities, paresthesia, EEG changes, and tremor. Abrupt discontinuation may also precipitate delirium, agitation, delusions, hallucinations, paranoid reaction, stupor, anxiety, depression and slurred speech;
Skin and Appendages
pruritus and diaphoresis;
neuroleptic malignant syndrome (see WARNINGS), allergic reactions including anaphylactic reactions, edema, fever, pathological gambling, increased libido including hypersexuality, and impulse control symptoms.
Read the entire FDA prescribing information for Symmetrel (Amantadine Hydrochloride)